Disclosed is a copolycarbonate composition including: a copolycarbonate having an aromatic polycarbonate-based first repeating unit and one or more aromatic polycarbonate-based second repeating units having siloxane bonds; and a polycarbonate, where the copolycarbonate composition has an impact strength at room temperature of 830 to 1000 J/m as measured at 23 ° C. in accordance with ASTM D256 (⅛ inch, Notched Izod), where the one or more aromatic polycarbonate-based second repeating units having siloxane bonds include a repeating unit represented by Chemical Formula 2 and a repeating unit represented by Chemical Formula 3: and where the copolycarbonate composition satisfies the following Equation 1: 1.0682×X+0.51